The purpose of this research is to learn the ethnosemantics of Mexican American fertility. It is designed to discover what are concepts about the appropriate role of planned parenthood for the family that are held by the Mexican Americans themselves. The investigation will utilize the techniques of ethnographic semantics to learn words which encode concepts of reproduction and its control that are acceptable to Mexican American men and women. These words will be collected in Southwestern American Spanish and English. The classification obtained will be correlated with variables that are likely to affect individual cognitions of reproduction and its regulation. Such variables include biological factors and their cultural determinants which can affect acculturation to western scientific medicine; the impact of the physical environment; and factors in the individual reproductive experience. Once the categories are discovered and their correlates studied, they will be used in the extension of the research to a larger Mexican American population, in order to learn who shares in this culture. The study is addressed to public health practitioners such as physicians, nurses and educators.